[SLAYER2003]

For those who have been following the various threads on the VP-Free issues and running a DRS,Here is what I can tell to be the best solution.

I have just modeled this to scale in SolidWorks. Obviously there are some slots missing for the roller. I Will put these in later.

This backplate would be for use with the 128mm BB and the etype derailer. The etype derailer would attach to this backplate like the current etype DRS backplate. It would also capture the seatpost mounted adaptor from Santa Cruz so as not to rotate if the plate did. The difference is that it is stepped so that it clears the chainstay and rotated slightly more to provide more tension in all gears.

I have limited access to CNC and I may have this made to try it out, but not very likely. I do believe something like this to be the best fix though.

Attached are two pics of the normal e-type DRS backplate and my new VP-Free specific model.

 

[dw]

I have some questions:

Nice modeling BTW!

1) Does this design actually clear the chainstay? What exactly do you mean by " clears the chainstay"

2) How much clearance is there between the back of the plate and the chainstay?

3) If the chainline is outside the chainstay, will the chain hit the chainstay in the top gears?


All in all, the stock DRS works really well on the vp frees, in spite of the "unique" features of the frame. Id be really worried about chain/chainstay interaction.

The best solution IMO really would be a swingarm that allowed chainguides in general to fit better. I notice that on a lot of frame designs, its almost like the chainguide and how it fits the bike is an afterthought.

If you build one let us know how it works out, it wont be cheap!

dw

 

[Castle]

DW,

I can kinda give you some more input on this....... btw slayer nice work!!!!


1. I believe Slayer is actually referring to the lower most drive side pivot..... it's what the guide hits that wont allow proper rotation......

2. On a Stock DRS the Back plate will not clear the lower most drive side pivot mounted properly, I achieved clearance using a 2.5mm b.b. spacer behind the backplate. When I did this, there was maybe 1mm (if that) between the pivot and my backplate. Also, if impacted hard and the guide was rotated the bolts/screws from the roller guard would hit the lower most drive side pivot, causing some gouging.. could get ugly!

3. There will be minimal Chain clearance from the bottom of the chainstay right where it curves in towards that lower most pivot. you can get the roller guard stuffed in there with some dremeling on the roller guard spacer plates...

It does seem as if you could position it to work in all gears and achieve proper chain tension...... it would be cutting it close and you would probably get a lil slap from the chain in some rough conditions.....


Slayer I'm gonna have to agree with ya, it looks like this may work..... You are still gonna have that gap between the back plate and 22t chainring in the front, for your chain to suck down into though...... or am I misssing something? I don't see anyway around it while utilizing the proper 55mm chainline....

 

[zane]

The modeling looks good, I wonder if anyone (besides santa cruz) has a computer-generated model of the vp-free? That'd be helpful in this situation, for any ambutious machinists and for E13.

 

[dw]

You are still gonna have that gap between the back plate and 22t chainring in the front, for your chain to suck down into though...... or am I misssing something? I don't see anyway around it while utilizing the proper 55mm chainline....

Not a lot of time right now but I jsut wanted to make a quick reply

The DRS does not guide the chain onto the top of granny. Our original prototypes did, but we found that the top guidance was not needed as long as proper chain tension/ roller placement, and derialleur setup were followed. The lower roller does a great job of keeping the chain from bouncing and derailling off of the granny.

Dave

 

[Incubus]

You can get a good indication of what botches things up by looking at VP-free build page on speedgoat's site. They ran into difficulty mounting x-type bb cups on their frame. This pic is from that site:

...and though the pic is on the non-drive side, I'm fairly certain it's the same on the drive side.

 

[Castle]

Not a lot of time right now but I jsut wanted to make a quick reply

The DRS does not guide the chain onto the top of granny. Our original prototypes did, but we found that the top guidance was not needed as long as proper chain tension/ roller placement, and derialleur setup were followed. The lower roller does a great job of keeping the chain from bouncing and derailling off of the granny.

Dave

However at this time, it's hard to get proper adjustment on a front der. while using the proper 55mm chainline....... I agree that it's not necessary, I had great luck with my DRS on a big hit and am still having great luck with one on my heckler.....

With this wider chainline that leaves a bigger gap it seems like the chain wants to jump down much more often.... from my understanding there will be a new front der. to address some of this in the near future.

 

[Castle]

You can get a good indication of what botches things up by looking at VP-free build page on speedgoat's site. They ran into difficulty mounting x-type bb cups on their frame. This pic is from that site:

...and though the pic is on the non-drive side, I'm fairly certain it's the same on the drive side.

that is only the non drive side, the drive side is offset the opposite way.

if you face the b.b. you will face through this. no big deal